Heterodi- and Heterotrinuclear Complexes Containing Highly Polar Metal−Metal Bonds

• Published in: Inorganic chemistry Vol. 38; no. 23; pp. 5295 - 5307
• Main Authors: Gade, Lutz H, Friedrich, Stefan, Trösch, Dominique J. M, Scowen, Ian J, McPartlin, Mary
• Format: Journal Article
• Language: English
• Published: American Chemical Society 15.11.1999
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic990350q

Reaction of the dichlorozirconium complex [CH2(CH2NSiMe3)2ZrCl2(thf)2] (1), containing a chelating amido ligand and having a trans disposition of the chloro ligands established by an X-ray diffraction study, with the carbonylmetalate derivatives K[MCp(CO)2] (Cp = C5H5) and Na[Co(CO)3(PPh3)] gave the heterotrinuclear complexes [CH2(CH2NSiMe3)2Zr{MCp(CO)2}2] (M = Fe (2), Ru (3)) and [CH2(CH2NSiMe3)2Zr{Co(CO)3(PPh3)}2] (4), respectively. Of these, 2 and 3 were structurally characterized by X-ray crystallography, establishing two unsupported metal−metal bonds in each of the compounds [2, d(Zr−Fe) = 2.665(2), 2.664(2) Å; 3, d(Zr−Ru) = 2.7372(7), 2.7452(7) Å]. Reaction of 2 and 3 with 1 in a 1:1 molar ratio led to a quantitative redistribution of complex fragments, yielding the dinuclear complexes [CH2(CH2NSiMe3)2(Cl)Zr−MCp(CO)2] (M = Fe (5), Ru (6). Both products as well as the Zr−Co complex [CH2(CH2NSiMe3)2(Cl)Zr−Co(CO)3(PPh3)] (7) were also obtained in moderate yields by reacting 1 with 1 molar equiv of the carbonylmetalate. Reacting 5−7 with NaCp gave the corresponding CpZr complexes [CH2(CH2NSiMe3)2(Cp)Zr−MCp(CO)2] (M = Fe (8), Ru (9)) and [CH2(CH2NSiMe3)2(Cp)Zr−Co(CO)3(PPh3)] (10), of which 9 was characterized by a single-crystal X-ray structure analysis [d(Zr−Ru) = 2.8297(14) Å]. Compounds 5, 6, 8, and 9 insert methyl isonitrile to give the heterobimetallic metallaiminoacylzirconium complexes [CH2(CH2NSiMe3)2(Cl)Zr{η2-C(NCH3)MCp(CO)2}] (M = Fe (11), Ru (12)) and [CH2(CH2NSiMe3)2(Cp)Zr{η2-C(NCH3)MCp(CO)2}] (M = Fe (13), Ru (14)), respectively. Reaction of the heterotrinuclear compounds 2 and 3 with isonitriles exclusively gave the products of the insertion into one of the unsupported metal−metal bonds, [CH2(CH2NSiMe3)2Zr{η2-C(NCH3)MCp(CO)2}{MCp(CO)2}] (M = Fe, R = Me, n Bu, Cy, Tol (15a−d); M = Ru, R = Me, n Bu, Cy, Tol (16a−d)). A crystal structure analysis of 16a established the insertion into one of the metal−metal bonds while the intact Zr−Ru bond was elongated in comparison to that of 3 [d(Zr−Ru) = 2.8639(6) Å]. Cleavage of both metal−metal bonds in 2 and 3 was observed in reactions with sulfoxides. Transfer of the S-bound oxygen atom to a carbonyl ligand led to CO2-linked trinuclear complexes in which the thioether thus generated was coordinated to the late transition metal center. The reaction at the two metal−metal bonds occurred cooperatively, precluding the isolation of intermediates.